Looking at your daughter (as my first thought went to weight as well) she is a solid girl but from her video doesn't appear to be overweight. I'm so sensitive about mentioning weight to teenage girls so I'd look at other options first.
One thing that helped me tremendously with back pain was Pilates. Does she do any type of stretching program?
One thing that helped me tremendously with back pain was Pilates. Does she do any type of stretching program?